Cassini ALE driver. (#110)

* Add getPosition with coefficients

* Add some exceptions and associated test

* remove debug statements and change test name

* Updated to use gsl for polynomial evaluation and separated out into a helper function. Swapped order of coeffs, other changes in response to review comments

* Added a couple of suggested tests and updated documentation

* Inital work toward ALE cassini driver

* Updated comments in base.py and removed notebook from this PR

* Update mk location to be accessible beyond my computer

* remove newlines

* Update name of Cassini ISS Ale driver

* Update comment based on feedback

ale/config.py

@@ -4,8 +4,9 @@ Config File
 
 # Directory with metakernals
 spice_root = "/data/spice/"
-cassini = '/data/big/spice/co-s_j_e_v-spice-6-v1.0/cosp_1000/extras/mk'
+cassini = '/usgs/cpkgs/isis3/data/cassini/kernels/mk/' # Cassini ISS
 mdis = '/data/spice/mess-e_v_h-spice-6-v1.0/messsp_1000/extras/mk' # Messenger
 mro = '/data/spice/mro-m-spice-6-v1.0/mrosp_1000/extras/mk' # Mars Reconnaissance Orbiter
 kaguya = '/data/spice/SELENE/kernels/mk/'
 dawn = '/data/spice/dawn-m_a-spice-6-v1.0/dawnsp_1000/extras/mk'
+

ale/drivers/base.py

@@ -577,7 +577,11 @@ class Pds3Label():
 
     @property
     def _exposure_duration(self):
+        # The EXPOSURE_DURATION may either be stored as a (value, unit) or just a value 
+        try:
             return self.label['EXPOSURE_DURATION'].value * 0.001
+        except:
+            return self.label['EXPOSURE_DURATION'] * 0.001  
 
 
 class NaifSpice():

ale/drivers/cassini_drivers.py

@@ -6,11 +6,11 @@ import spiceypy as spice
 import numpy as np
 
 from ale import config
-from ale.drivers.base import Framer, RadialDistortion, Driver, Pds3, NaifSpice
+from ale.drivers.base import Framer, RadialDistortion, Driver, Pds3Label, NaifSpice
 
-
-class CassiniIssPds3NaifSpiceDriver(Driver, Pds3, NaifSpice, Framer, RadialDistortion):
+class CassiniIssPds3LabelNaifSpiceDriver(Driver, Pds3Label, NaifSpice, Framer, RadialDistortion):
     """
+    Cassini mixin class for defining Spice calls.
     """
     id_lookup = {
         "ISSNA" : "CASSINI_ISS_NAC",
@@ -28,6 +28,7 @@ class CassiniIssPds3NaifSpiceDriver(Driver, Pds3, NaifSpice, Framer, RadialDisto
           Path to latest metakernel file
         """
         metakernel_dir = config.cassini
+
         mks = sorted(glob(os.path.join(metakernel_dir,'*.tm')))
         if not hasattr(self, '_metakernel'):
             for mk in mks:
@@ -39,8 +40,8 @@ class CassiniIssPds3NaifSpiceDriver(Driver, Pds3, NaifSpice, Framer, RadialDisto
     def instrument_id(self):
         """
         Returns an instrument id for unquely identifying the instrument, but often
-        also used to be piped into Spice Kernels to acquire IKIDs. Therefore they
-        the same ID the Spice expects in bods2c calls.
+        also used to be piped into Spice Kernels to acquire instrument kernel (IK) NAIF IDs. 
+        Therefore they use the same NAIF ID asin bods2c calls.
 
         Returns
         -------
@@ -73,12 +74,7 @@ class CassiniIssPds3NaifSpiceDriver(Driver, Pds3, NaifSpice, Framer, RadialDisto
         return [0.0, 0.0, 1/pixel_size]
 
     @property
-    def _exposure_duration(self):
-        # labels do not specify a unit explicitly
-        return self.label['EXPOSURE_DURATION'] * 0.001  # Scale to seconds
-
-    @property
-    def odtk(self):
+    def _odtk(self):
         """
         The radial distortion coeffs are not defined in the ik kernels, instead
         they are defined in the ISS Data User Guide (Knowles). Therefore, we
@@ -90,3 +86,15 @@ class CassiniIssPds3NaifSpiceDriver(Driver, Pds3, NaifSpice, Framer, RadialDisto
         elif self.instrument_id == 'CASSINI_ISS_NAC':
             # NAC
             return [float('-8e-6'), 0, 0]
+
+    @property
+    # FOV_CENTER_PIXEL doesn't specify which coordinate is sample or line, but they are the same
+    # number, so the order doesn't matter
+    def _detector_center_line(self):
+      return float(spice.gdpool('INS{}_FOV_CENTER_PIXEL'.format(self.ikid), 0, 2)[1])
+
+    @property
+    # FOV_CENTER_PIXEL doesn't specify which coordinate is sample or line, but they are the same
+    # number, so the order doesn't matter
+    def _detector_center_sample(self):
+      return float(spice.gdpool('INS{}_FOV_CENTER_PIXEL'.format(self.ikid), 0, 2)[0])